The invention relates to an optical assembly with a detector and an imaging optical system, and with a laser, the emitting a beam parallel to the object-side optical axis of the optical system.
In particular the invention relates to an all-around seeker scanning a substantially hemispherical solid angle and to a laser, which emits a laser beam parallel to the respective instantaneous optical axis of the scanning optical system.
An important application of the invention is a device for detecting guided missiles with optical seeker head and for generating a laser beam directed to the seeker head of such guided missiles. The device comprises an all-around seeker having a detector, which responds to the thermal rdiation from the guided missile, and having a laser the beam of which can be directed to a guided missile detected by the detector.
Guided missiles have a seeker head with a detector, which usually responds to infrared radiation. The seeker detects a target to be attacked, such as a fighter aircraft, and provides guidance signals, which guide the missile to the target. In order to protect the target from such guided missiles, equipment is provided on the target for detecting attacking guided missiles. To this end, xe2x80x9call-around seekersxe2x80x9d have been used. Such an all-around seeker contains a detector which, in turn, responds to thermal radiation emitted by the guided missile. An imaging optical system, which generates an image of an object scenario on the detector, continuously scans a large, for example hemispheric, solid angle If an attacking guided missile is detected, xe2x80x9ccounter measuresxe2x80x9d have to be taken. On such counter measure consists in directing, upon detection of a guided missile, a high intensity laser beam onto the seeker head of this guided missile. Thereby, the detector of the seeker head is xe2x80x9cdazzledxe2x80x9d and, if possible, destroyed. Then the seeker head no longer xe2x80x9cseesxe2x80x9d the target. Then the fighter aircraft can avoid a hit by evasive manoeuvres.
Similarly, an assembly of the type described above with all-around seeker and laser may be provided also on a missile, in order to make sensors of the attacked aircraft, by means of which the aircraft detects the attacking missile, inoperative and, thereby, to make evasive manoeuvres more difficult.
It is an object of the invention, to provide an optical assembly with a detector and a laser, wherein the laser beam is always directed to the object scenario detected by the detector.
It is a more specific object of the invention to provide a compact and reliable design of such an optical assembly.
A still further object of the invention is, to provide an optical assembly of the type mentioned above which permits scanning of large solid angles by the detector and also directing a laser beam to any location within this large solid angle.
To this end, the optical assembly comprises a structure-fixed detector defining a detector plane. A roll-pitch gimbal system is provided having a roll gimbal rotatable about a roll axis relative to said structure, and a pitch gimbal rotatable relative to said roll gimbal about a pitch axis orthogonal to said roll axis. An imaging optical system is mounted on said roll-pitch gimbal system and defines a detector path of rays and an object-side optical axis and comprises optical means for directing radiation incident along said optical axis onto said structure-fixed detector in each position of said roll-pitch gimbal system. The optical assembly further comprises laser means for generating a laser beam in a laser path of rays, said laser means comprising a structure-fixed laser. Furthermore, there are laser reflecting means mounted on said roll-pitch gimbal system for directing said laser beam in a direction parallel to said optical axis in each position of said roll-pitch gimbal system.
Thus there is a roll and pitch gimal system. Such a gimbal system permits large angles between the object-side optical axis of the imaging optical system and the roll axis. Therefore, a large solid angle of, for example 2xcfx80, i.e. 180xc2x0 in each radial plane, can be covered by the all-around seeker. Both the dtector and the laser are structure-fixed. This facilitates the power supply and the picking off of signals. Both the radiation emitted by the detected object and directed onto the detector, and the the laser beam are routed over optical elements on the roll and pitch gimbal system, whereby parallel alignment of object-side optical axis and laser beam can be ensured. Thereby, the laser beam is automatically directed to, for example, a guided missile detected by the imaging optical system an the detector.
An embodiment of the invention will be described in greater detail with reference to the accompanying drawings.